The Biffis Canal Hydrodynamic System Performance Study of Drag-Dominant Tidal Turbine Using Moment Balancing Method

Round 1

Reviewer 1 Report (Previous Reviewer 2)

This manuscript proposed a new drag-dominant tidal turbine using moment balancing method. The topic is very interesting and some comments are presented as follows,

1. For the grid independent test part, the selected mesh schemes were not rigorous. The power coefficient still increase as the grid elements increase, which means the selected gird number is not enough.

2. The tables should be three-line tables.

3. As can be seen from Figure 1, the interaction between turbines should be considered in the actual situation, but it is not considered in the current simulation.

4. This paper does not introduce the formula of the governing equation, but introduces the formula of the turbulence model. Why the current turbulence model was chosen needs to be explained.

5. The paper lacks the description of the verification part, how to ensure the accuracy of the calculation method and results in this paper, in other words, errors in simulation and results need to be analyzed. Is there any experiments for these simulations？

6. In the table 4, the Validation for Characteristic Optimal TSR values, the error percentage of pinwheel are very large..

7. This paper studies a small hydropower unit, some other forms of small hydropower can also be introduced in this paper. For example, DOI: 10.1016 / j.r ser. 2022.112786, DOI: 10.1016 / j. nergy. 2022.124630, DOI: 10.1016 / j.r enene. 2021.01.014

Minor editing of English language required

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report (Previous Reviewer 1)

CFD simulation is interesting, but please add a section to explain all steps of simulation briefly.

You need to add a discussion part. CFD simulation part is extensive and there is not a discussion part. 

Please more explain about table 1. why we need ti know that? Did you compare them during the research?

Plesae provide more information about grid independence test and why that is necessary

What is your references for formulas?

 

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report (New Reviewer)

Overall, the article is written correctly, with no major concerns about the content.
Nevertheless, the paper contains quite a few question marks:
I do not really understand why turbines of different types (vertical and horizontal axis of rotation), with different natures of operation and different ranges of parameters for the operating point, are juxtaposed. A broader justification for this choice would have been advisable.

The authors carry out the analysis for scale models, justifying the reduction of computational power requirements, when at the same time, one of the most important advantages of CFD methods is the possibility to model the operation of objects on a scale of 1:1. Scaling objects always introduces additional error and at the same time increases the difficulty of assessment or comparison with other objects.

Results with an error of a few dozen percentage points are unlikely to be reliable. The reasons for such large differences should be checked.

Line 134, the unit - superscript - in square metres should be corrected.

Author Response

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Author Response File: Author Response.docx

Reviewer 4 Report (New Reviewer)

Please refer to the attached document.

Comments for author File: Comments.pdf

None.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report (Previous Reviewer 2)

The manuscript is recommended accepted in current form

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Dear Authors, the paper is well-written but needs some improvements.

- In the last paragraph of the introduction, you mentioned what the paper wants to explain but I can not see the problem statement and why the paper try to answer this paragraph.

- Methodology is clear.

- Discussion needs more explanations

- The conclusion part can not support your introduction and extensive methodology. Please revise it and add more explanations.

Author Response

Enclosed file

Author Response File: Author Response.docx

Reviewer 2 Report

Recommendation: Minor revisions.

In this paper, a new net moment balance algorithm with less calculation time, cost-effectiveness and user-friendliness is proposed, which combined with the analysis of hydrodynamic characteristics of numerical simulation results of hydraulic turbine flow field based on CFD technique, and can be used to determine the optimal blade tip speed ratio of tidal turbine, thus providing theoretical basis and engineering reference for the development of tidal turbine. As a conclusion, the manuscript is innovative, the results provided are sufficient to support the claims made. The reviewer suggests that with minor revisions, this manuscript is qualified for publication in the journal.

However, some comments are presented as follows:

1) Figure 1 shows the computational domain of numerical simulation, but only the boundary conditions of the entrance and exit are given in the figure, and the necessary contents such as the boundary conditions around the channel are lacking. The author should perfect this part.

2) In this study, k-ε turbulence model is applied to simulate two types of tidal energy turbines, so it is necessary to give the CFD control equations. The author is requested to add the above contents.

3) The “#” in Eq. 6 represents what meaning? This seems strange, and the author needs to explain the above problems.

4) The position of the arrow indicating the width of the error range in Fig. 7(b) does not seem to be in the right place, so please check it by the author.

The Quality of English Language is acceptable

Author Response

see enclosed file

Author Response File: Author Response.docx

Reviewer 3 Report

The manuscript titled "Parametric Optimization Analysis of Pinwheel and Savonius Drag-Dominant Tidal Turbines Performance with Moment Balancing Method" claims to develop a novel method to find the optimal TSR of any turbine with a cost-effective and user-friendly Moment Balancing algorithm to support robust tidal energy development. However, the article lacks clarity and coherence in its presentation of ideas, the main parts of the work are two CFD simulations instead of the algorithm. The Net Moment Balancing Equation in Table 3 has different coefficients coming from nowhere and is not explained in the text. Overall, this article is not suitable for publication. 

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Thank you for new version of the paper. I believe that conclusion part can be more better. But, I would like to accept the paper.

Reviewer 3 Report

This reviewer still finds this paper difficult to understand in a way that cannot be accepted for publication.  Even not judge the scientifc aspect, this manuscript is not suitable for publication, for example:

The term "Disk Actuator theory", appearing at the second line in the abstract, never exists in this field.  It is never called that way, even in the reference (9) selected by the authors, it is not called "Disk Actuator". But this word repeats many times in this manuscripts.

In figure 2, the author named the figure with "isometric view", which is again not the case, it is a perspective view.

In equation (1), the channel width = 0.6 ,without any unit, is not approperiate. 

Why equation (14) start with an english word "asinefficiency" ? It is not a proper way to present scientific result.  

The newly added part (216) includes a description on the k-epsilon turbulence model, whereas the from lines 321 the author discusses the k-omega turbulence model. 

Dear